This invention relates to devices and in particular fluid line coupling devices which are suitable for connecting pneumatic line segments, hydraulic lines segments, fuel line segments or other fluid line segments, tubes, ducts, conduits, and the like. More specifically, this invention relates to self-locking coupling devices which are designed to prevent inadvertent disassembly and as a result are capable of operating in severe vibrational and thermal cycling environments while maintaining a leak-free fluid connection.
A variety of coupling devices are known in the art for connecting pressurized fluid line segments and the like. Many of these devices have been specifically designed to prevent inadvertent disassembly and catastrophic leakage during operation. These devices include conventional lock-wire fluid fittings which consist of threaded fittings coupled together by wired fasteners which prevent the nut components from loosening during operation. However, conventional lockwire fluid fittings are labor intensive to install and as a result are not a preferred coupling system where multiple couplings are required in a single installation.
Other devices include, for example, U.S. Pat. No. 5,083,819 to Bynum which discloses a threaded fluid coupling equipped with a fastener capture device. The coupling devices comprises an internally threaded female fitting formed with external flats about its circumference and an externally threaded male fitting configured with a plurality of tangs mounted above the external threads in a circumferential fashion. Upon engagement of the male and female fittings, the tangs contact the flats with an interference fit and rachet about the junctions between the flats until the fittings are securely coupled. Once coupled, the tangs and the flats cooperate to inhibit rotation of the nut relative to the mating fitting to prevent an inadvertent disassembly of the coupling.
U.S. Pat. No. 5,058,930 to Schlosser discloses a pressurized fluid coupling device consisting of a coupling component with internal threads which engage the external threads of a nipple. The coupling component includes a cylindrical arrangement of cantilevered fingers with bulbous tips at their ends projecting radially inward which, upon engagement of the respective internal and external threads, ride up a frusto-conical ramping surface on the nipple until the tips drop into an annular groove in the nipple wall. Cantilevered forces in the fingers created as the bulbous tips press against the threads and serve to minimize the effects of vibration thereupon. The bulbous tips seated in the annular groove are intended to prevent a complete disconnecting of the coupling component from the nipple, a separation which could cause catastrophic leakage at the joint.
Although the above described coupling devices can be used effectively in some applications, these devices lack positive locking features and as a result can be disconnected by simply applying a torsional force to the coupling members sufficient to overcome the retaining features which are intended to inhibit relative rotation and prevent disassembly of the coupling.
What continues to be needed and hereto unavailable is an improved self-locking coupling device, which, once securely coupled, resists disconnection due to torsional forces applied to the respective coupling members.
In accordance with a preferred embodiment of the present invention, a self-locking coupling device for coupling to a fitting having a radially outwardly facing groove is provided with a coupling body having a central bore and an axially extending collar including a radially projecting throughbore with retention shoulder and a spring element positioned in the throughbore with one end abutting the retention shoulder. An actuating pin including a radially projecting stem terminating in a locking tab and first and second catches proximate an opposing end with the pin inserted through the spring element and radially outwardly biased thereby. A rotatable locking ring mounted concentrically about the collar in close fitting relationship includes a first slot and a second slot corresponding respectively to the first and second catches. The locking ring is operable to rotate relative to the collar to engage the first catch with the first slot to dispose the locking tab within the throughbore and also operable to rotate so as to engage the second catch with the second slot to dispose the locking tab within the central bore to engage, when axially aligned with the groove of the fitting to restrict axial displacement of the coupling body relative to the fitting.
In another aspect of the present invention, a threaded head portion is provided for coupling a threaded fitting to the grooved fitting via the coupling body.
Yet another aspect of the present invention is the inclusion of a bendable retention flange at the free end of the collar for restraining the locking ring.
Another feature of the present invention provides an indicator indicating the position of the locking tab when the pin engages one of the slots.
Another aspect of the present invention may be found in the provision of a radially projecting exterior button atop the pin which extends through first slot when the pin is in a locked position and projects into the second slot when the pin is in an unlocked position.
Another feature of the present invention is a stop shoulder in said axially projecting bore to engage an alignment shoulder on the grooved fitting when inserted into the coupling body to axially align the groove with the pin.
In one embodiment of the present invention the pin includes a multi-tiered enlarged latch head for engaging the slots.
Other aspects of the present invention will become apparent with further reference to the following drawings and specification.